The present invention relates generally to a power source switch, and more particularly to an electrical switch.
As shown in FIG. 1, an electrical switch 1 of the prior art comprises a case 2, two power source terminals 3a and 3b which are disposed in the case 2, a conductive piece 4, a touch switch structure 5, and a spring piece 6. The conductive piece 4 is fastened at one end with the power source terminal 3a. The touch switch structure 5 has a push button 5a and an action rod 5b disposed under the push button 5a. The push button 5a is disposed over the case 2. The action rod 5b is connected at the free end with other end of the conductive piece 4. The spring piece 6 is connected with other end of the conductive piece 4 such that the spring piece 6 urges the action rod 5b. In operation, the push button 5a is first pressed to cause two ends of the conductive piece 4 to make contact with the two power source terminals 3a and 3b, thereby resulting in the current flow. When the conductive piece 4 is overloaded, the conductive piece 4 is caused to deform by heat. As a result, the spring piece 6 is forced to jump upwards, so as to push the action rod 5b to displace upwards. The conductive piece 4 and the spring piece 6 are actuated to move upwards to bring about the separation of the conductive piece 4 from the power source terminal 3b, thereby resulting in interruption of the flow of the electric current. In light of the spring piece 6 urging only one side of the action rod 5b, the action rod 5b is apt to move aside. In addition, the extent of deformation of the conductive piece 4 is often dependent on the climatic factors as well as the nature of the material of which the conductive piece 4 is made. In other words, the conductive piece 4 and the spring force 6 of the prior art electrical switch are not reliable at best. The prior art electrical switch is thus a potential fire hazard.
The primary objective of the present invention is to provide an electrical switch which is capable of a precision interruption of the flow of an electrical current.
The electrical switch of the present invention comprises a housing in which at least two power source terminals are fixedly disposed such that one of the two terminals is connected with a conductive piece which is disposed in the housing for conducting or interrupting electrically the two terminals. A link structure comprises a push button which is pivoted in the housing, and a support rod fastened at one end with the push button. The support rod is connected at other end with the conductive piece such that an external force enables the support rod to cause the conductive piece to make contact with or to separate from other one of the two power source terminals. A spring piece is fastened with the housing and the support rod of the link structure. When the current of the conductive piece is excessive, the spring piece is so heated as to jump to cause the conductive piece to separate from other one of the two terminals. An adjustment device is exerted on by a predetermined force to change the condition of being heated by the conductive piece under the circumstance that the conductive piece is electrically connected with the two power source terminals.